Work is continuously being done to provide maximum protection in the area of air filtering while minimizing discomfort to the wearer of a mask designed for air filtering and purification.
The type of respirator to which the present invention is related is the respirator which utilizes a half-mask or full face mask which covers the nose and mouth and/or the entire face.
In attempting to increase protection afforded through the use of a mask-type respirator a two-point seal has previously been disclosed. Matheson, et al., U.S. Pat. No. 4,414,973, teaches the use of a stiffening outer flange, or lip seal comprising a blunt edge and internal to that a curved seal to more easily conform to a wearer's face. Likewise, Lehmberg, U.S. Pat. No. 2,166,164, teaches the use of an internal and external seal but only in the cheek area. The Lehmberg respirator double seal is very similar to Matheson, et al. in that it comprised a blunt outer and a curved inner seal.
The present invention increases the integrity of the seal through the employment of multiple flexible contact surfaces between the mask and the face. Two or more contact surfaces are used, the one most external being a flexible inturned lip and the remaining one or more being flexible and feathered inward toward the face creating multiple pressure pockets.
The further addition of horizontal pleats in a horizontally elongated frontal portion of the mask allows greater jaw and mouth movement for ease of talking with less shifting of the seal, thereby maximizing protection by the mask against the intrusion of unfiltered air. Although Fink, U.S. Pat. No. 2,376,871, teaches the use of corrugations or ribs to permit jaw movement, these extend from the jaw hinge points on one side of the face to the other. The present invention uses pleats only on the front of the mask with a wrap around design of the mask, covering the jaw area. Location of these pleats provide a comfortable fit to wearers of varied sizes.
Increased comfort is also provided by use of this invention through the location of the inhalation and exhalation ports on the mask releasing expelled air directly and allowing fresh air to enter laterally and bathe over the face, keeping the enclosed portions of the wearer's face cool.
It is a primary object of the present invention to provide an orinasal respirator with an improved seal to exclude air from passing between portions of the mask and the face of the wearer even during movement, thereby lowering physical restrictions generally created by use of a respirator.
It is a further object of the present invention to provide for vertical expansion and contraction of the mask during movement of the mouth to decrease seal shifting thereby creating a seal with added integrity.
It is another object of the present invention to increase wearer comfort by facilitating the immediate release of hot, moist expelled gases through the location of an exhalation port or ports in the direct line of expelled breath and locating the inhalation ports on the outer sides of the mask so as to allow fresh, cool air to circulate over the wearer's face.